Thermochemical decomposition

Bishara, A., Salman, O.A., Khraishi, N., Marafi, A. 1987. Thermochemical decomposition of hydrogen sulfide by solar energy. Int J Hydrogen Energy 12 679-685. 

Brecher, L.E., S. Spewock, C.J. Warde (1977), The Westinghouse Sulfur Cycle for the Thermochemical Decomposition of Water , International Journal of Hydrogen Energy, Vol. 2, pp. 7-15, Pergamon Press. 

Pyrolysis (Irwin, 1979, 1982 Tomasik et al., 1989b) is the decomposition of a substance at elevated temperatures, principally by dry heat. Low-temperature pyrolysis arbitrarily refers to thermochemical decomposition in the 121.1-... 

Research on methods of hydrogen production by thermochemical decomposition of water has been carried out in several laboratories with increasing interest during the last decade. 

Thermochemical Decomposition of H2S with Metal Sulfides or Metals... 

Although H2S is at present a by-product of the desulfurization of fossil fuels on a large scale, only the recovery of free sulfur is carried out by the Claus treatment. On the other hand, the application of H2S decomposition as an H2 evolution method is proposed for use in the thermochemical process undertaken for water splitting. Thus, the thermochemical decomposition of H2S has wide-spread applications in various field. 

In the thermochemical decomposition of water, chemical reactions, as well as heat, are used to split water into its components. One such system involves the following reactions (the temperature required for each is given in-parentheses) ... 

Note 2 More efficient methods than electrolysis for obtaining hydrogen from water are under investigation. One of these is thermochemical decomposition. Another is photochemical decomposition by solar radiation, either directly or via a solar power generator. Photolytic decomposition of water with platinum catalyst has been achieved. Hydrogen can also be obtained by photolytic decomposition of hydrogen sulfide with cadmium sulfide catalyst. 

At the present time, in Russian radiochemical production processes solutions of tributyl phosphate (TBP) in hydrocarbon diluents are used most extensively in extraction processes, while the anionite VP-lAP is used in sorption processes. Available information on the thermochemical decomposition of these reagents with nitrate oxidizers makes it possible to gain some idea of the potential danger of the processes that occur in them. 

The thermochemical decomposition of organic-chlorine and organic-phosphor CW in oxygen environment (these account for the absolute majority of the Baltic dumped chemical weapons) permits them to be reduced to some easy-to-decontaminate or harmless compounds like carbon dioxide, phosphorus oxides or hydrogen chloride, sulphur oxides. The processes take place in combustion chambers at 3,000-3,500°C and a pressure of several MPa, using methods traditional for liquid-propellant rocket engines. The end combustion products of other CW might be additionally condensed to trap the hazardous compounds. 

The terms thermal decomposition, pyrolysis, and carbonization often may be used interchangeably. However, it is more usual to apply the term pyrolysis (a thermochemical decomposition of coal or organic material at elevated temperatures in the absence of oxygen, which typically occurs under pressure and at operating temperatures above 430°C [800°F]) to a process that involves widespread thermal decomposition of coal (with the ensuing production of a char—carbonized residue). 

Kumta and co-workers [20] have used a three-step sol-gel-based procedure to prepare ternary transition metal nitrides involving heat treatment under ammonia of a metal organic hydroxide precursor. This route consists in the hydrolysis of a polymeric liquid precursor to form a metal-organic hydroxide. Thermochemical decomposition of the metal-organic hydroxide precursor under ammonia leads to ternary nitrides such as NijMOjN, FeWN and Ti AIN. DiSalvo and co-workers incorporated alkaU metal ions to increase the stability of the nitrides compared to binary compounds. They used a sol-gel-based route to prepare ternary alkali and alkaline-earth metal nitrides such as NaTaN, KTaN and NaNbN [21, 22]. 

Shackelford, S.A., Coolidge, M.B., Goshgarian, B.B., Loving, B.A, Rogers, R.N., Janney, J.L. and Ebinger, M.H. (1985) Deuterium Isotope Effects in Condensed-Phase Thermochemical Decomposition React ions of Octahydro-1,3,5,7-tetrani tro-1,3,5,7-tetrazoc ine Journal of Physical Chemistry 89, 3118-3126. 

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